The present invention relates to an endoscope apparatus and more particularly, to an air and water supply mechanism employed in the endoscope apparatus.
When the coeliac cavity of a human body is viewed using the endoscope, mucus and leftovers are often adhered to the surface of a viewing window of the endoscope to disturb the field of view. The conventional countermeasure of preventing the disturbance of viewing field was to attach to the foremost end of the endoscope a nozzle through which water was jetted to clean the viewing window and air was then jetted to the viewing window to remove water drops left on the surface of the viewing window. This air supply to remove water or water drops from the surface of viewing window (which will be hereafter referred to as water removing air supply) is more effective and the field of view through the viewing window can be restored more quickly when the force to supply air is large.
On the other hand, in addition to removing water or water drops from the surface of viewing window, water removing air supply also serves to inflate the coeliac cavity to some extent, thus taking the coeliac cavity ready and easy to be viewed. This air supply to inflate the coeliac cavity (which will be hereafter referred to as normal air supply) sometimes causes such danger that the coeliac cavity is ruptured when an air supply pressure is too high. It is therefore desirable to keep the air supply pressure low in normal air supply.
The conventional endoscope apparatus had a pump to supply air and water and the pump was driven at same output (or pressure) to supply air and water. This made it dangerous to set supply pressure high and supply pressure was kept low accordingly. The capability of cleaning the viewing window was therefore low and water or water drops were not completely removed from the surface of the viewing window either after cleaning. In other words, the field of view was neglected for the sake of safety.